Thromboelastometry versus free-oscillation rheometry and enoxaparin versus tinzaparin: an in-vitro study comparing two viscoelastic haemostatic tests dose-responses to two low molecular weight heparins at the time of withdrawing epidural catheters from ten patients after major surgery
2015 (English)In: BMC Anesthesiology, ISSN 1471-2253, E-ISSN 1471-2253, Vol. 15Article in journal (Refereed) PublishedText
Background: Monitoring low molecular weight heparins (LMWHs) in the perioperative period is prudent in patients at high risk of coagulative complications, especially when the patient has an epidural catheter requiring withdrawal, which is associated with the risk of spinal haematoma. The aim of this study was to evaluate the in vitro dose-responses of two different LMWHs on two different viscoelastic haemostatic tests, using blood sampled from patients with normal routine coagulation parameters, on the day after major surgery when their epidural catheters were due to be withdrawn. Methods: Enoxaparin or tinzaparin were added in vitro to blood from ten patients who had undergone oesophageal resection, to obtain plasma concentrations of approximately 0, 0.5, 1.0 and 1.5 IU/mL. Coagulation was monitored using thromboelastometry (ROTEM (R)) using the InTEM (R) activating reagent; and free oscillation rheometry (FOR: ReoRox (R)), activated using thromboplastin. Clot initiation was measured using ROTEM-CT, ReoRox-COT1 and ReoRox-COT2. Clot propagation was measured using ROTEM-CFT, ROTEM-Alpha Angle and ReoRox-Slope. Clot stability was measured using ROTEM-MCF and ReoRox-Gmax, and clot lysis was measured using ROTEM-ML and ReoRox-ClotSR. Results: Clot initiation time assessed by thromboelastometry and FOR was prolonged by increasing concentrations of both LMWHs (P < 0.01). Equivalent doses of tinzaparin in international units (anti FXa units) per millilitre prolonged clot initiation more than enoxaparin (P < 0.05). There was significant inter-individual variation - the ranges of CT and COT1 at LMWH-concentrations of 0 and 1.5 IU/mL overlapped. None of the tests reflecting clot formation rate or stability showed a dose-response to either LMWH but clot lysis showed a tentative negative dose-response to the LMWHs. Conclusions: Clot initiation times dose-dependent prolongation by LMWHs in this study agrees with previous research, as does tinzaparins stronger anti-coagulative effect than enoxaparin at equivalent levels of anti-FXa activity. This casts doubt on the validity of using anti-FXa assays alone to guide dosage of LMWHs. The significant inter-individual variation in dose-response suggests that the relationship between dose and effect in the postoperative period is complicated. While both ROTEM and FOR may have some role in postoperative monitoring, more research is needed before any conclusion can be made about their clinical usefulness.
Place, publisher, year, edition, pages
BIOMED CENTRAL LTD , 2015. Vol. 15
Coagulation; Factor Xa; Thromboelastometry; Free-oscillation rheometry; Low molecular weight heparin; Postoperative; Enoxaparin; Tinzaparin; Epidural haematoma; Spinal haematoma
IdentifiersURN: urn:nbn:se:liu:diva-123800DOI: 10.1186/s12871-015-0145-2ISI: 000365587500002PubMedID: 26603039OAI: oai:DiVA.org:liu-123800DiVA: diva2:892920